Apparatus for transmitting pressure from a corrosive fluid to a noncorrosive fluid



March 1959 A. J. HILDENBRANDT, JR 2,

APPARATUS FOR TRANSMITTING PRESSURE FROM A CORROSIVE FLUID TO A NON-CORROSIVE FLUID Filed Oct. 11, 1955 INVENTOR. AUGUST J. HILD ENBRANDT JR.

W/YM ATTORNEY.

United States Patent M APPARATUS FOR TRANSMITTING PRESSURE FROM A CORROSIVE FLUID TO A NON- CORROSIVE FLUID August I. Hildeubrandt, Jr., Elizabeth, N. 1., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application October 11, 1955, Serial No. 539,803

8 Claims. (Cl. 137-787) A general object of the present invention is to provide simple and effective means for separating two chambers where one of the chambers encloses a corrosive liquid under pressure while maintaining liquid pressure communication between the chambers until a predetermined overload pressure is reached. The invention finds application particularly in combination with liquid pressure measuring instruments which must be protected from corrosive liquids and excessive overload pressures.

The invention is characterized by the arrangement of inner and outer flexible bags which I have devised. In the preferred practice of my invention, 1 make use of a resilient outer bag and a flexible or slack but relatively non-resilient inner bag with a liquid filled space between. The outer bag is positioned within a rigid wall enclosure which is open at one end and is filled with a liquid in the space between the outer bag and the wall. Said outer liquid filled space is in communication with a further hollow space extending from the open end of the enclosure and this contains the liquid which surrounds the outer bag. A wire screen covers the aforementioned opening and separates the last mentioned space from the space wherein the outer and inner bags are located. The inner bag which is contacting the corrosive liquid'has relatively small or no substantial stretching capacity and is spaced away from the outer bag which is resilient and adapted to be stretched to cover said opening.

The purpose and effect of the described arrangement is to permit a limited expansion of the outer bag without subjecting the inner bag to an internal expanding force when the pressure of a corrosive liquid is applied to the inner wall of the inner bag.

With the described arrangement which I have devised, the inner and outer bags and the liquid filled spaces surrounding these bags, operate collectively on an increase of the pressure within the inner bag, to subject the outer bag to a stretching force.

The arrangement disclosed has the advantage in that it permits the outer resilient bag or boot to be expanded by the pressure acting on the non-corrosive liquid in the space between the two bags without subjecting the inner bag to an objectionable bag expanding force.

It is accordingly a further object of the present inven tion to provide a liquid isolating and overload protecting means between a, pair of chambers where that means comprises a stretchable or resilient bag for overload protection and a slack bag for isolating the resilient bag from a corrosive liquid under pressure.

The various features of novelty which characterize my invention are pointed out with particularity in the claims 2,877,799 Patented Mar. 17, 1958 annexed to and forming a part of this specification. For a better understanding of the invention, however, its ad-, vantages, and specific objects attained with its use, ref-:

erence should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of theinvention.

- The accompanying drawing illustrates a practical embodiment of the essential elements of the present invention.

The end of the element B remote from the element A is internally threaded for closure by a tubular elementD having a threaded outer wall screwed into an internally; threaded opening E in the end portion of the memberB remote from the member A. As shown, the member D has a central passage F with its inner end in communication with the central chamber or passage H of the container B through a porous body G. That body may well be, and is shown as a woven wire screen or more advantageously made of a metal disc containing large drilled holes. The outer end of the central passage F, is

normally closed in any suitable and convenient manner.

For example, the passage F may well be connected to an unillustrated measuring chamber and thereby provide usable measures of the pressures in the chambers F and H.

The chamber H contains an outer resilient bag I and the latter surrounds a relatively non-resilient inner flexible bag J. The bags I and I have outturned flanged end portions clamped between the flanged end portions a and b of the members A and B, and extend from the space between the flanges a and b into proximity With the screen G. Each of the bags I and J is closed at its end remote from the flanges a and b by an integral rounded bag end portion. As shown, the outer surface of the bag I is spaced away from the inner surface of the wall B, and from the screen G, by a liquid containing space K, and the inner side of the bag I is spaced away from the bag J by a liquid containing space L. In nor mal operation, the liquid at each side of the bag I is compressed by the pressure of the corrosive liquid in the space within the bag J. a

As shown, the bag J is slack or corrugated so that when pressure is applied to its inner side it may expand without stretching. Ordinarily, also, the pressure forces applied to the body portion of the bag I will have little or no significant effect on the thickness or shape of the body portions of the bags I and J. The primary purpose of the bag arrangements described, is to provide a way by which the effect of a pressure increase in the corrosive liquid acting on the inner side of the bag J may be trans mitted through the non-corrosive liquid in space L to the bag I, without subjecting that bag I to objectionable stress.

The described arrangement provides efiective transmission of pressure from a corrosive liquid to a noncorrosive liquid with overload protection. It is well adapted, for example, to serve as a pressure seal for use in a linear flow meter of conventional type. The re The embodiment of the invention illustrated by way.

silient bag I provides overload protection by stretching and sealing against the wire screen G. The low resilience bag I provides this protective effect without being required to stretch. A practical advantage of the arrangement is that it takes into account the fact that the required resilience for overload protection and resistance to various corrosive liquids do not generally occur in a single material. The described arrangement permits the bag or boot I to expand into its seal position against the wire mesh screen G before the low resilient boot I is expanded into a position in which objectionable stretching of the bag I will occur.

It-should be readily understood that when this seal is used in the aforementioned flow meter the,bag I should contain a few wrinkles so it will not go taut and thus introduce a spring effect into the system while the meter is'beingoperated within its normal calibrated range. It should also be understood that as the uppermost value of this normal range is approached these wrinkles will gradually be removed and that no wrinkles will be in the bag I at an instant of time just before this uppermost range value is reached. At this time the bag I will become taut and as soon as the meter hits its maximum range value this taut bag will be stretched by the pressure applied thereto into engagement with the screen G so as to afford the aforementioned overload protection.

Advantageously and as shown, the central passage F in the member D is coaxial with, but smaller in'di'arneter than the tubular body B, and the latter'is provided with a circular flange M underlying the adjacent end of the annular body D. In consequence, the annular rim portion of the screen G which engages the end of the hollow body D, is clamped between the latter and the flange M. As shown, the side of the flange M adjacent the screen G, isat right angles to the tubular member B, butthe other side of the flange M is tapered in correspondencewith the rounded form of the adjacent end of the bag I. In consequence, a small movement of liquid into and out of the space K can occur without it having a significant efiect on the size or shape of the bag I.

While the filling medium in the spaces F, K, and L is disclosed as being of any non-corrosive liquid it 'shoud be understood that any suitable fluid, such as a gas, could be effectively used as this filling medium. It should further be understood that where it is desired to use the overload protecting seal of the present invention to protect e. g an instrument from a corrosive fluid, such as a gas, rather than from a corrosive liquid as described proper care should be taken to make sure that the material selected for the bag I is impervious to the corrosive gas.

While, in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed with'out departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Apparatus for transmitting pressure from a'corrosive 'fluid container to a non-corrosive fluid container with overload protection, comprising in combination a first irregularly curved slack wall of a non-stretchable resilient material, surrounding a space containing a corrosive fluid, a'second wall of flexible resilient material surrounding a fluid containing space between said first and second walls, a rigid third wall surrounding said second wall and a fluid containing space between said second and third walls.

2. In apparatus for transmitting pressure-from a dormsive'fluid container to a non-corrosive fluid container with overload protection; the combination of a flexible, first slack sack of non-stretchable material having its open end portion fixedly attached and opening into a container retaining a corrosive fluid under pressure, a flexible wall of resilient material surrounding said sack and having its outer peripheral portion fixedly attached to said con tainer, a non-corrosive fluid between said sack and said flexible wall, a rigid wall surrounding said flexible wall, a fluid containing space between said flexible and rigid Walls, a pervious wall portion forming a part of said rigid wall and acting as a fluid connection between a non-corrosive fluid container external of said rigid wall and said fluid containing space except when the pressure of said corro sive fluid is of snflicient magnitude to force said flexible wall against said pervious wall.

3. In apparatus for transmitting pressure from a corrosive fluid to a non-corrosive fluid with overload protection; the combination of an irregularly curved first slack wall of non-stretchable material surrounding a' body of corrosive fluid under pressure, a second curved wall of resilient material surrounding and spaced away from the first wall and separated from the latter'by a non-corrosive liquid containing space, a rigid wall surrounding said second wall, liquid interposed between said second and said rigid wall, and said first wall being subjected to an expanding force of said corrosive fluid under pressure to compress the liquid between said first and second walls and said liquid between said second and rigid walls.

4. In apparatus for transmitting changes in fluid pressure from a corrosive fluid container to a non-corrosive fluid container with overload protection; the combination of a first flexible concave, slack wall of a substantially non-stretchable material fixedly secured at its outer periphery and adapted to contain a corrosive liquid under pressure therein, a second flexible concave wall of resilient material surrounding and spaced from said first wall having its outer peripheral portion fixedly secured to the peripheral portion of said first wall, a non-corrosive fluid between said first and second walls, a container providing a rigid third wall surrounding said second wall, a fluid between said second and third walls, apervious wall portion forming a part of said third wall through which said fluid in said fluid containing space between said second and third wall may be forced upon an increase in the pressure of said corrosive liquid.

5. A rupture proof apparatus for transmitting a pressure of a corrosive liquid to a non-corrosive liquid comprising, an irregularly curved slack bag of non-stretchable material having a corrosive liquid under pressure acting on its inner surface, a flexible bag of resilient material surrounding and peripherally attached to said first bag, a filling material between said bags and a fixedly mounted chamber surrounding and peripherally attached to said second bag containinga non-corrosive transmitting liquid.

6. Apparatus for transmitting pressure from a corrosive fluid container to a non-corrosive fluid container with overload protection, comprising in combination a first irregularly curved slack wall of a substantially nonstretchable material surrounding a space containing corrosive fluid, a second wall of flexible resilient material surrounding a fluid containing space between said first and second walls, a rigid third wall surrounding said second wall and a fluid containing space interposed between said second and third walls.

7. A rupture proof apparatus for transmitting a pressure of a corrosive liquid to a non-corrosive liquid comprising, an irregularly curved slack bag of a substantially nonstretchable material having a corrosive liquid under pressure acting on its inner surface, a flexible bag of resilient material surrounding and spaced from said first bag, a filling material between said bags and a. fixedly mounted chamber surrounding and spaced from said 'sive fluid to a non-corrosive fluid with overload protec tion; the combination of an irregularly curved first slack wall of a substantially non-stretchable material surround- ReferencesClted in the file of this patent ing a body of corrosive fluid under pressure, a second curved wall of flexible resilient material surrounding and UNITED STATES PATENTS peripherally attached to the said first wall and separated 1,452,039 Gravell Apr. 17, 1923 from the latter by a non-corrosive liquid containing space, 5 2,095,752 La Brie Oct. 12, 1937 a rigid wall surrounding said second wall, liquid inter- 2,097,985 Maryott Nov. 2, 1937 posed between said second and said rigid walls, and said 2,152,467 Crosby Mar. 28, 1939 first wall being subjected to an expanding force of said 2,207,807 Hopkins July 16, 1940 corrosive fluid under pressure tending to compress the 2,371,632 Lippincott Mar. 20, 1945 liquid between said first and second walls and said liquid 10 2,628,673 Ericson Feb. 17, 1953 between said second and rigid walls. 2,639,613 Richmond May 26, 1953 

